In the semiconductor manufacturing process, there is employed a process to grind the rear surface of semiconductor wafer (hereinafter simply referred to as “wafer”) into a thin thickness. In the grinding process, the surface of the wafer (circuit forming surface) is stuck with a protective sheet to cover the same, and after completing the grinding operation in this state, the protective sheet is peeled off from the wafer.
As for a peeling apparatus for the protective sheet, for example, as disclosed in the Patent document 1, Japanese Patent Application Laid-open No. Hei 11-16862, there is known an apparatus in which an adhesive tape is stuck to the end portion of protective sheet; and by pulling the adhesive tape, the protective sheet is peeled off from the wafer. And as disclosed in the Patent document 2, Japanese Patent Application Laid-open No. 2003-197583, there is known an apparatus in which an adhesive tape is stuck in a direction across a protective sheet; and by pulling the adhesive tape, the protective sheet is peeled off from the wafer.
The peeling apparatus disclosed in the Patent document 1 employs an arrangement such that the adhesive tape is stuck to the end portion of the wafer in a manner of heat fusion sticking. Therefore, even when grinding dust of the wafer adheres onto the protective sheet, the connection between the adhesive tape and the protective sheet is possible without being affected by the grinding dust. However, this peeling apparatus has the following disadvantages. That is, when a protective sheet having a high stress absorbing property i.e., a protective sheet of a soft material is used, sometimes the protective sheet spreads out and drops down to stick to a dicing tape on which the wafer stuck and supported thereby; thus, the material for the protective sheet is limited. Further, since this arrangement employs the heat fusion sticking, in this point also the material for the protective sheet is limited. Furthermore, the protective sheet peeling angle according to the Patent document 1 turns over the protective sheet in an obtuse angle direction of almost 180°. Therefore, in the case where, in order to satisfactorily hold the extremely thin wafer, a rigid protective sheet, for example, a thick protective sheet is employed, the peeling itself is difficult.
On the other hand, in the arrangement according to the Patent document 2, the protective sheet is peeled off by using a peeling roller movable in the direction across the protective sheet while rotating on the protective sheet. In this arrangement also, the protective sheet is peeled off in an obtuse angle direction. Therefore, the arrangement according to the Patent document 2 also has a disadvantage such that, when a rigid protective sheet is stuck on the wafer, the protective sheet is difficult to be peeled off satisfactorily.